def menu():
    print("Login System")
    print("1 to login")
    print("2 to register")
    print("x to exit")
    return input("choose an option: ")

def login():
    while True:
        answer=input("Would you like to login? ")
        if answer=="yes":
            username=input("Enter your username: ")
            password=input("Emter your password: ")
        else:
            break

def register():
    while True:
        answer=input("Would you like to register? ")
        if answer=="yes":
            username=input("create a username: ")
            password=input("create a password: ")
        else:
            break
while True:
    choice=menu()
    if choice=="1":
        login()
    elif choice=="2":
        register()
    elif choice=="x":
        break
    else:
        print("not a valid choice")

def menu():
    print("Quiz selection")
    print("--------------")
    print("H for History")
    print("C for Computer science")
    print("M for Music")
    print("X to quit")
    return input("choose an option")

def History():
    while True:
        answer=input("would you like to take the quiz in easy medium or hard level? ")

while True:
    choice=menu()
    if choice=="H":
        History()
    elif choice=="C":
        Computer_science()
    elif choice=="M":
        Music()
    elif choice=="X":
        break
    else:
        print("not a valid option")